Renderers can also be used with code that uses namespaces. When creating or overriding new renderers with namespaces, be sure to use "output" as the second level namespace to comply with the rules for namespaces. Non-namespaced renderers can be overridden by a namespaced renderer and vice-versa - this leads to a complex search strategy when looking for overridden renderers.

You do not have to use autoloading namespaced classes.

If you really want to use that in your case you should:

Place the renderer file in the classes/output

File should be named mod_hvp_renderer.php

Inside you must specify appropriate namespace .

namespace theme_mytheme\output;

Class name should be mod_hvp_renderer and should extend \mod_hvp_renderer